Hi pichenettes. Shortcut buttons for important pages is a good idea We’ll think it over…

‘SUB’ button is for SubMenu in pages
’LOAD’ button will be very much used to load samples and more.
‘RND’ button is for random values in different pages
’Rectangle and arrow’ button for play and stop function from sequencer
’W/S’ button selected samples ore waveforms in the osc page

this this at first a early preview how the DE-Generator can look. An i agree with you , page buttons are usefull , because there are a lot of Pages . Actual Rolf and me discuss Loop modulation by Mod Matrix and also Wavetable synthesis … Actual all User Waves - Waveforms- not samples- can change easy
by copy it on the SD card… I mean the OSC waves AND the LFO waves.

The Waves ars 256 Bit long- mono- and in RAW format .
Simply use a free Editor like Wavosaur to generate your own Waves in Raw format and copy it in the Degenerator as new LFO waves- for Example .

The OSC waves are organized in 256 bit but 64 in chain. So all waves together have a 32 Kbyte file. But you can also use a normal Sample as a complete waveform with 32kByte . This is split into Waves in 256 Byte …
We have made the OSC/LFO section very flexible.

All firmwars - samples and Waveforms are on the SD card . This means - if you cange the SD card it can be a new instrument The Degenerator can play now Samples up to 18…20 seconds .
18…20 seconds in one shot - or with loop . Loop in sustain- release. With loop no time limitations.
Resampling - Filter out to Audio In is also possible. The new Waveform you can store direct to the SD card and use it imdiately for your sounds.
And much more …
The memory DS is organise for example in 100 Banks with 128 Sounds .
Each Sound stores its own Sample in a preset ! But there is also a Main Preset Bank !
If you change the Sample or delete one main Sample -a copy is keep save in the Preset .
So you can’t loose the sounds - Thanks Rolf .

Timeline …
I think i start with the PCB’s now in january ,. Rolf draws actual the schematics and i have made the first - look and feel - GUI design.
Next i update my website with new infos/Pictures about the DE-Generator.

From a prakical perspective, I would keep the midi and power/gate leds closer to the display, like in beta 3, to avoid having a too large UI-pcb or loose Midibox-style wiring.

The volume knob… I would prefer the buttons at the bottom and the volume knob at the top. Most synths put the volume knob at the top. You don’t operate it very often and touching it by accident can be problematic, especially live. With the knob on the top, its less likely to happen.

The shortcut buttons are a good addition! They could be color coded (e.g. grey)

I tried to edit your image to reflect my ideas. I would prefer the volume at the top right (from a usability and construction perspective) but the it looks too crammed on the right side…

Hey …
I’ve changed the external audio input in the DE-GENERATOR. Now has the possibility to sample the stereo input signal at the sum signal. Further, the input signal is also switched to the filter inputs. For the mini scope function of the stereo output is switched to the same ADC input. This saves components and board space.

For better sample recording, I have connected the ADC input in Xmega processor as a differential input. The ADC is sampling in Xmega processor with 12bit and a sampling rate of 44.1KHz. Internally, the 12-bit value is reduced to 8bit and written into 1MByte large sample RAM. The OpAmp IC 15c + 15d makes a fifferential audio signal for the ADC input.

In the DE:GENERATOR I have implemented a Noise Shaper function for better sample recording. The ADC input works with a resolution of 12 bits. For internal sample calculations I have downsampling from 12 to 8 bits (4 * right shifting). But recordung quit audio signals it has loud noise . The Noise Shaper moves this noise in a higher frequency range, so you hear the noise not so loud.

To demonstrate this I have added some sound samples. Respectively without and with the noise shaper function. Most clearly we hear it in sound 3 +4. The piano sounds are very quiet and you can here a loud noise floor from 8Bit resolution.

There’s one thing that puzzles me in your schematics: since the input is AC coupled, it seems to me that the voltages at IC15c’s and IC15d’s outputs swing below GND. How does the AVR handle that? The ADC input pin won’t be happy to receive the negative voltage.

I might be wrong about this because I just had a look at your schematics for 2 mins, but I suspect that currently, ADC_In- only sees the positive half of the signal, and ADC_In+ only sees the negative half of the signal - because these signals swing below 0. Which explains why you have to use differential mode to make it work. But even then, the performance won’t be good because of the clamping - the two “halves” of the signal won’t exactly sum up to the original signal.

Have you tried the simpler solution which consists in adding 1.25V to the signal so it wiggles between 0V and 2.5V (for example by feeding -2.5V through a 20k resistor to IC15c ; or 2.5V through a 20k resistor to IC15d). It might save you an ADC channel!

Could you post oscilloscope traces of the signal hitting both ADC_input+ and ADC_input-

It seems to me that you’re sampling only the positive half of the signal on one side, and the negative half of the signal on the other side. Once you take the difference you get the full signal of course, but you’re probably getting crossover distortion if your circuit works this way.

My suggestion is to add a DC offset of 1.25V to the signal before it hits the ADC.

I’ve tried single adc input with dc offset on the xmega cpu (see above the penultimate circuit) and it was a bad NSR result. I have made a monitor function for reording in the DE:GENERATOR and you can here an sample directly. The differecial mode is the best sample result